This invention relates to optical communications and, in particular, to optical communications systems in which information is transmitted by soliton or soliton-like pulses.
Laboratory demonstrations have recently been reported of soliton transmission in systems where the dispersion was not uniformly anomalous along the fibre, instead being periodically compensated by fibre of opposite (normal) sign dispersion. In this manner transmission was achieved at 20 Gb/s over 9000 km in a recirculating loop, and 8100 km in a straight line experiment. These figures are substantially in excess of what has previously been achieved without the use of soliton control techniques such as sliding filters and synchronous modulators. While it is thus clear that there are significant benefits to be gained from adopting dispersion management in soliton systems, to date there has been little conceptual explanation of the mechanisms behind this improvement.